The Bayer-Hall process has been virtually the only process used for the commercial production of aluminum for the nearly 100 years since these processes were invented. The Bayer process to make alumina, which is electrolyzed in the Hall process to make aluminum metal, requires the use of high grade bauxites. The United States today is 92% dependent on the importation of bauxite for the operation of its current aluminum plants. The prices for this bauxite have increased nearly five-fold in the last two years and there exists an element of uncertainty of continued dependable supply because of political and economic situations abroad.
It is therefore very much to the interest of the United States and many other countries worldwide to be able to economically make alumina for the current Hall aluminum process plants from respective domestic ores. For instance, there is an established reserve of Georgia kaolin clay with sufficient alumina content to supply the domestic aluminum industry for over 500 years. Progress has been made on research on extraction of alumina from abundant clays with some pilot plants announced but said work has been limited to the use of mineral acids, nitric, hydrochloric and sulfuric, and all these processes cost considerably more than the Bayer process in both capital and manufacturing costs even with the higher bauxite costs prevalent today.
Additionally, the Hall process requires exorbitant amounts of electrical energy, a factor acting as a serious barrier to the growth of the domestic industry. Licenses for new plants have been denied in view of the power crunch. Older plants have had difficulty in maintaining production.
Two new aluminum-making process claims to use much less power. One process is being piloted by Alcoa and involves the direct electrolysis of aluminum chloride made by chlorination of Bayer alumina. The lowest power Toth process makes aluminum in a chemical manner by reacting the aluminum chloride with manganese metal to make aluminum metal and manganese chloride, the latter then being recycled into its component elements. This process, too, uses aluminum chloride.
Therefore, there exists a crying need for the development of a process that would be able to make from abundant domestic ores metallurgical grade aluminum chloride in anticipation of these newer aluminum developments with lower power costs, and also being able readily to convert that aluminum chloride to alumina for the current Hall plants and should that process somehow continue to be the modus operandi. The term metallurgical grade means a material of sufficient purity from which aluminum metal could be made of quality equal or superior in quality to that produced by the Bayer-Hall process.
The present invention comprises a process to make pure aluminum chloride and/or pure alumina fully of metallurgical grades from domestic clay, and furthermore can advantageously utilize high and low grade bauxites and other aluminous ores present in certain parts of the United States and in many countries abroad to promote competitive raw materials for supplying this and other countries.
The primary purpose of this invention is to make pure aluminum chloride and/or pure alumina in accordance with the current and future demands of the aluminum industry from abundant aluminous ores and in economic competition and superior to the Bayer process. Ecology of the present invention is devoid of the problems of the Bayer process problems like disposal of large volumes of caustic red mud. The residues of the current invention are dry solids readily disposable.
While much data on various independent chlorinations and purifications of aluminous ores have been known from the prior art, some by the current inventors, there has not been developed and demonstrated a total process to achieve the required urgently needed objectives of the current invention for the economic production from domestically abundant clay and other widespread aluminous ores, of aluminum chloride and/or alumina of satisfactory purity and economy required by the current and upcoming aluminum manufacturing plants.